Southern California -- this just in

U.S. Secretary of State Hillary Rodham Clinton condemned the killing of four American yachters -- including two from Southern California -- allegedly at the hands of Somali pirates.

Clinton said the case underscores the need for a more coordinated approach to protecting vessels going through areas where Somali pirates prey.

"This deplorable act by the pirates that stalk vessels in the waters off of Somalia firmly underscores the need for the international community to act more decisively together," she said. "We’ve got to have a more effective approach to maintaining security on the seas, in the ocean lanes that are so essential to commerce and travel."

Jean and Scott Adam of Southern California and Phyllis Macay and Robert Riggle of Seattle were killed on the yacht several days after it was hijacked off the coast of Oman.

The daughter and son-in-law of Scott Adam issued a statement late Tuesday thanking the U.S. Navy for the attempted rescue of the four hostages.

"We would like to express our deepest gratitude to the brave men and women of the Navy and other military branches who risked their lives trying to save them," said a statement issued through the FBI by the Sem family of Escondido. Their first names were not revealed.

FBI agents were with the Sem family Tuesday as news of the killings was made public.

"Our loved ones were tragically taken from us and our hearts are broken," said the family statement, which asked for the media to respect their privacy.

Accounts of the killings varied Tuesday and could take some time to sort out.

The Adams were headed toward the Red Sea and then the Greek islands on Friday when, according to U.S. military officials, pirates boarded the Quest off the coast of Oman.

Almost immediately, U.S. naval vessels began shadowing the yacht, negotiating for the Americans' release as the vessels made their way south toward Somalia, said Lt. Col. Mike Lawhorn, a spokesman for the U.S. Central Command, part of an international coalition of anti-piracy operations in the Indian Ocean.

There were signs of dissent among the pirates. On Monday, two of them abandoned the yacht and came aboard the guided-missile destroyer Sterett.

Then on Tuesday morning, the pirates fired a rocket-propelled grenade at the Sterett, which missed, according to the U.S. military. As some pirates came on deck with hands raised, as if trying to surrender, a team of 15 Navy SEALs boarded the yacht amid small-arms fire. President Obama had authorized the use of force if the military determined that the hostages' lives were in imminent danger, the White House said.